The Next Release of CCSM: IPCC and Community Applications Bill Collins National Center for Atmospheric Research Boulder, Colorado

Development History of CCSM June 1996 New ocean, land, sea-ice models New physics in atmosphere CCSM 2.0 May 2002 New physics in all models CCSM 3.0 Winter 2003

Configuration of CCSM for IPCC Atmosphere (CAM 3.0) T85 (1.4o) Land (CLM2.2) T85 (1.4o) Sea Ice (CSIM 4) (1o) Coupler (CPL 6) Ocean (POP 1.4.3) (1o)

Component Models in CCSM Atmosphere Multiple dynamical cores: SLD, Eulerian, & Finite Volume Generalized 2D decomposition of grid Resolutions with most heritage: T31, T42, and T85 (L26) Ocean Derivative of LANL Parallel Ocean Program Grid: spherical in S. hemisphere, orthogonal curvilinear in N. hemisphere Standard resolution: 320 x 384 (L40) Land Surface Superset of NCAR LSM and Georgia Tech BATS Same horizontal resolution as atmosphere 10 layers for soil, up to 5 for snowpack Sea Ice Up to 5 categories of sea-ice thickness

Atmospheric Dynamics and Resolution Goal for IPCC: T85 (1.4o) or equivalent FV resolution Improved resolution for regional impact studies Improved resolution for fidelity in coastal stratus regions Recommendation on atmospheric dynamics: Eulerian for standard IPCC scenario applications Finite Volume for future development and experimentation Goal for CCSM: Single physics package for multiple dynamics & resolutions: T85 11 T42 22.5 T31 …. IPCC AMWG, CVWG, Paleo, … Resolution BGCWG Dynamics

Main Model Biases in CCSM2 Overestimation of winter land surface temperatures Bias largely eliminated in new CLM and CAM Underestimation of tropical tropopause temperatures Bias reduced in new CAM Erroneous cloud response to SST changes Signs and pattern of response corrected in new CAM Errors in E. Pacific surface energy budget Stress, latent heat flux, and insolation better in T85 CAM Double ITCZ and extended cold tongue Cold tongue mitigated in new POP Underestimation of tropical variability Underestimation still present

Winter Land Surface Temperatures

Tropical Tropopause Temperatures

Cloud Forcing Response to Tropical SSTs

East Pacific Surface Energy Budget

Double ITCZ

Tropical Variability

Ocean Model Changes for CCSM 3.0 KPP boundary layer Solar Absorption (Chlorophyll) Double Diffusion Ideal Age and Passive Tracer Infrastructure Ocean Currents in Air-Sea Fluxes

Mixed Layer Depths CONTROL All Physics + Numerical MODS Jan July

SST Signature of Solar Absorption

SST Signature of All Ocean Modifications

Land Model Working Group Goal For CCSM2: state-of-the-art model with focus on biogeophysics, hydrology, river routing Goal For Next Few Years: Natural and human-mediated changes in land cover and ecosystem functions and their effects on climate, water resources, and biogeochemistry Process: Continue to develop and improve existing physical parameterizations in the model while adding new biological and chemical process Biogeophysics Hydrology Latent Heat Flux Sensible Heat Flux Photosynthesis ua Momentum Flux Wind Speed Precipitation Diffuse Solar Radiation Longwave Radiation Evaporation Interception Canopy Water Direct Solar Radiation Transpiration Reflected Solar Radiation Emitted Long- wave Radiation Throughfall Stemflow Absorbed Solar Radiation Sublimation Evaporation Infiltration Surface Runoff Melt Snow Soil Heat Flux Soil Water Heat Transfer Redistribution Drainage

Model Development for new CLM Biogeochemistry Goal: Enable parameterization of terrestrial carbon cycle New hierarchical data structures within a grid cell: grid cell  land unit  snow/soil columns  plant functional types. Does not change climate. Allow multiple plant types on a single soil column. Minor climate changes. Biogeophysics I Goal: Minor changes or bug fixes Allow precipitation to be rain/snow mix Improve 2-m temperature diagnostic Remove discontinuity in bulk density of snow Biogeophysics II Goal: Reduce excessive summertime temperatures in arid regions. Reduce Arctic winter warm temperature bias Turbulent exchange of heat from ground

Turbulent Heat Flux from Vegetated Surfaces CLM2.2 CLM2

Effects on Land Surface Temperatures CLM2.2 CLM2 22-year (1979-2000) simulations of CAM2 with CLM2.2 CLM2.2 significantly cools surface air temperature

Changes to Physics in CAM3 Clouds and condensate: Improved prognostic cloud water & moist processes Transfer of mixed phase precipitation to land surface Improved cloud parameterization Radiation: Shortwave forcing by diagnostic aerosols Updated SW scheme for H2O absorption Updated LW scheme for LW absorption and emission Surface models: Introduction of CLM 2.2 Reintroduction of Slab Ocean Model (SOM) Energy fixers for dynamics + diagnostics

Increased Cloud Condensate CAM 3 CAM 2 Separate cloud liquid and ice variables Advect cloud condensate Include latent heat of fusion Use ice & water variables for cloud optics New dependence on temperature for cirrus particle size Sedimentation of cloud droplets and ice particles Modified evaporation of rain CAM 3 – CAM 2

Increased Cloud Amounts CAM 3 CAM 2 PBL height constrained Rain rate > 0 Convection cloud amounts from convective mass fluxes Stratocumulus clouds in lowest 2 levels Changes to autoconversion thresholds Changes to relative humidity thresholds Fall speed of droplets is function of effective radius CAM 3 – CAM 2 NETTOA = 4.5 Wm2 NETTOA = 0.53 Wm2

Global Aerosol Assimilation Climatology 1995-2000 Aerosol Assimilation AVHRR Analysis Aerosol Forcing Analysis NCAR CAM Climate Impacts

Addition of Prescribed Aerosol Forcing

Changes in Longwave Cooling Rates: New H2O Lines and Continuum Change in LBL Cooling Change in CAM Cooling

Global Decrease in Longwave Fluxes

Changes in Shortwave Heating Rates: New H2O Lines and Continuum Tropics LBL Heating CAM2 Heating CAM2x Heating

Global Increase in SW Heating Rates

Global Decrease in Surface Insolation

Higher Tropopause Temperatures CAM 3 CAM 2 CAM 3 – CAM 2

Lower Winter Land Surface Temperatures CAM 3 CAM 2 CAM 3 – CAM 2

Cloud Response to Tropical SST Variations

Changes in Coupler & the Sea-Ice Model Improved performance and scaling Greater flexibility to add new fields Significant DOE communication infrastructure Faster multi-way communication to components Sea Ice Horizontal advection scheme Addition of constant salinity in sea ice Updates to albedos of snow and sea ice Updates to ridging for thick ice categories

Surface Temperatures: CCSM T85 Control

Sea-Ice Area: CCSM T85 Control

Sea-Ice Thickness: CCSM T85 Control

Land Surface Temperatures: T85 Control

Tropical Surface Stress: T85 Control

Surface Insolation: CCSM T85 Control

ENSO Variability: CCSM T85 Control

Nino Index Variability: CCSM T85 Control

Changing Resolution: Surface Stress

Changing Resolution: Surface Insolation

Changing Resolution: Total Precipitation

Changing Resolution: Sea-Surface Temperature

Changing Resolution: Pacific Temperature

Changing Resolution: Surface Salinity

Changing Resolution: Pacific Salinity

Changing Resolution: Pacific Currents

Decision Schedule for IPCC Recommendation for IPCC configuration: CCSM Scientists’ Meeting, Nov. 12 Data for decision: T85 integrations for 3 options of 50+ years T85 SOM integrations for 1x, 2xCO2 T85 AMIP/warm-cold integrations (ENSO) Analogous data for T42 Final evaluation and decision for IPCC: SSC Meeting, Nov. 18-19

Release of CCSM3 to the Community Contents of release: Model physics: all components = IPCC Model data sets: controls for T31,T42, & T85 Technical documentation Schedule for release: Winter 2004 Documentation in literature: J. Climate special issue? Release of IPCC model data sets?

Climate Sensitivity: T42 CAM + SOM

IPCC Schedule

Scenarios: IPCC Fourth Assessment Report

NCAR’s IPCC Production Schedule CCSM Execution Speed on NCAR IBM: T42 ATM: 10.9 years/day T85 ATM: 4.3 years/day

Development Plans for CCSM, 2004-08

CCSM: The Next Two Years Roadmap to the future Climate sensitivity from IPCC studies Process studies from GFDL collaboration, CPTs Studies of higher resolution and “benchmark” calculations News physics/dynamics from Science Plan Integration of climate and chemistry Ocean and land biogeochemistry Prognostic aerosols Tropospheric chemistry WACCM Tracers

The Evolution of CCSM

Computational Demands for CCSM Science

Conclusions A new version of CCSM is ready for IPCC Features of CCSM3: Improvements in component physics Ability to run with multiple resolutions, dycores Issues for the near future: Final decisions regarding model configuration Definition of public release Completion and analysis of IPCC integrations Integration of coupled carbon-climate experiments Issues for the longer term: Addition of new scientists in emerging focal areas Access to significant new computational resources

Sea-Ice Concentration: CCSM T85 Control

Changing Resolution: Arctic Salinity

Changing Resolution: Temperature Cycle